Задача N5431 теория вероятностей доверительный интервал

5431. x̅=20, n=100, σ=5. Find the confidence interval for estimating with a reliability of 0.9 the unknown mathematical expectation a of a normally distributed feature X of the general population, if the standard deviation σ=5, the sample mean x̅=20 and the sample size n=100.

Detailed solution. Decorated in Microsoft Word 2003 (Quest decided to use the formula editor)